From a non-elite/semi-casual/PvM-minded perspective, having non-instanced access to Nyd Garb is incredibly bias towards the "elite" and virtually limits access to the select few on this server who will have a monopoly on it if it were implemented in the same format as Valk Randgris and Satan Morroc.
You are denying 95% of the server from experiencing the content which should be equally available for everyone.
The original implementation (instanced, quest-driven, lengthy cooldown, etc) was perfect and allowed a wider variety of players to participate and enjoy this portion of the end-game.
This effects me on a personal level because the anticipation of exploring and experiencing the Nidhogger Dungeon is essentially all that has been keeping me playing this server. If you take this away from people like me, who just want to experience all that this game has to offer, and give it to those few who have the luxury to camp a spawn every time it's up thus denying anyone else on the entire server from essentially playing this game...then I just don't know what to say.
Please, PLEASE do not implement this in a fashion that denies most of the server from playing and enjoying this server. Please, if at all possible, implement this as it was meant to be. If that is impossible: Please at least keep it instanced as to allow everyone on the server an equal opportunity to experience this game to the fullest.
tl;dr: Non-instanced Nyd Garb means only a handful of people get to participate. Please at least keep Nyd Garb accessible via instance.